The invention relates to a semiconductor device comprising a 4-phase charge-coupled device having a semiconductor body a surface of which comprises a row of electrodes to which clock voltages can be applied for storing and transferring electric charge packets. The electrodes are arranged in groups of four, the first electrode of each group being connected to a first clock line, the second electrode being connected to a second clock line, the third electrode being connected to a third clock line and the fourth electrode being connected to a fourth clock line. The last electrode of the row is connected to a separate connection and is present beside a reading stage, the capacitance of which is sufficiently large to comprise the maximum charge packet which can be stored below two adjacent electrodes.
In conventional charge-coupled devices, the reading stage is formed by the output. The usual output structure comprises an output zone or diode which is usually connected to the gate electrode of a MOST-follower and can be set at a given potential via a resistor or a reset switch. The last electrode which is present before the output zone is usually termed the output gate and is preferably set at a fixed potential. In the case of an n-channel CCD, said potential is near the most negative potential of the transport clock voltages, and, in the case of a p-channel CCD, it is near the most positive potential of the clock voltages. As a result of this the crosstalk of the clock voltages on the output signal can be reduced. Moreover, since each charge is stored in the output diode, the output capacity is kept restricted.
It is to be noted that the reading stage need not necessarily coincide with the output structure of the device but that a part of the register may be present between the reading stage and the output. Moreover, the output capacitance may be formed by a MOS-capacitor instead of by a diode, the insulated gate of said MOS being connected to the MOST-follower.
In the conventional mode of operation of a 4-phase CCD one charge packet the value of which is determined inter alia by the value of the electrode, can be handled per four electrodes. In the book "Charge Transfer Devices" by C. H. Sequin and M. F. Tompsett, edited by Academic Press, New York, 1975, pp. 64/65 it is stated that the charge capacitance (signal value) can be doubled by using overlapping clock voltages so that charge can always be stored below two juxtaposed electrodes.